Matakuliah
Tahun
Versi
: D0472/PERANCANGAN ELEMEN MESIN
: 2005
:
Pertemuan 1
PERTIMBANGAN DAN PROSEDUR
UMUM DESAIN
1
Learning Outcomes
Pada akhir pertemuan ini, diharapkan
mahasiswa akan mampu :
– mengidentifikasikan pertimbangan
dan prosedur yang harus diambil
dalam proses desain
2
Outline Materi
•
•
•
•
•
•
•
Pendahuluan
Pertimbangan Umum Desain
Prosedur Umum dalam Desain
Besaran dan Sifat Material
Pembebanan dan Tegangan
Material Selection
Safety Factor
3
Pendahuluan
How design
depend on
viewpoint of the
individual who
define the
problems
[George E.
Dieter, 1991]
4
5
PERTIMBANGAN UMUM DALAM DISAIN
• Type of load and stressed
• Motion of the parts
• Selection of materials
• Form and size of the parts
• Gesekan dan pelumasan
• Use of standard parts
• Safety of operation
• Workshop facilities
• Number of part to be manufactured
• Cost
• Assembling
6
PROSEDUR UMUM DALAM DISAIN
• Make a complete statement of the problem
• Select mechanism which will gived the
desired motion
• Find the forces acting on each member
• Select the materials best suited for each
member
• Find the size of each member
• Modify the size to agree with manufacture
facilities.
• Draw the detailed drawing of each component
7
PEMILIHAN MATERIAL
Classification of Engineering Materials ???
8
9
PEMILIHAN MATERIAL
PROPERTIES OF MATERIALS
•
•
•
•
•
•
Physical ?
Electrical ?
Mechanical ?
Thermal ?
Chemical ?
Fabrication ?
10
PEMILIHAN MATERIAL
The most important properties
•
•
•
•
•
•
Tensile strength
Shear strength
Modulus (elasticity, shear)
Elongation
Yield strength
Hardness
11
PEMILIHAN MATERIAL
Faktor yang dipertimbangkan :
•
•
•
•
•
•
•
•
•
Performance
Safety
Risk
Environmental impact
Aesthetics
Machineability
Cost
Recyclability
BEBAN
12
BEBAN DAN TEGANGAN
•BEBAN (LOAD)
•TEGANGAN (STRESS)
•REGANGAN (ELONGATION)
•TEGANGAN TARIK (TENSILE STRESS)
•TEGANGAN TEKAN (COMPRESSIVE STRESS)
•TEGANGAN GESER (SHEAR STRESS)
Shear Force : A good example of shear force is seen with a simple
scissors. The two handles put force in different directions on the pin that
holds the two parts together. The force applied to the pin is called shear force.
•MODULUS YOUNG
•TEGANGAN DUKUNG (BEARING STRESS)
•TEGANGAN TEKUK (BENDING STRESS)
13
A Static Load : A good example of this is a person
seen on the left. He is holding a stack of books on his
back but he is not moving. The force downwards is
STATIC.
A Dynamic Load : A good example of a dynamic load
is the person on the right. He is carrying a weight of
books but walking. The force is moving or DYNAMIC.
Tension : The rope is in “tension” as the
two people pull on it. This stretching puts
the rope in tension.
Compression : The weight lifter finds that
his body is compressed by the weights he
is holding above his head.
14
SAFETY FACTOR
It is defined, in general, as the ratio of the maximum
stress to the working stress, mathematically,
FS 
Max stress
Working or design stress
In case of ductile materials, the factor of safety is based
upon the yield stress. In case of brittle is based on
ultimate stress.
The selection of proper FS to be used in designing
machine components depends upon a number of
consideration, such as: the materials, mode of
manufacture, types of stress, general service conditions
and shape of the parts.
15
DESAIN CONSIDERATION
16
17
18
PENUTUP
• Pertimbangan dan prosedur dalam
perancangan suatu elemen spesifik untuk
elemen tersebut.
• Pertimbangan dan pemilihan prosedur
merupakan kunci perancangan.
19